powerpc/powernv: Fixes for hypervisor doorbell handling

Since we can now use hypervisor doorbells for host IPIs, this makes
sure we clear the host IPI flag when taking a doorbell interrupt, and
clears any pending doorbell IPI in pnv_smp_cpu_kill_self() (as we
already do for IPIs sent via the XICS interrupt controller).  Otherwise
if there did happen to be a leftover pending doorbell interrupt for
an offline CPU thread for any reason, it would prevent that thread from
going into a power-saving mode; it would instead keep waking up because
of the interrupt.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/dbell.c

@@ -17,6 +17,7 @@
 
 #include <asm/dbell.h>
 #include <asm/irq_regs.h>
+#include <asm/kvm_ppc.h>
 
 #ifdef CONFIG_SMP
 void doorbell_setup_this_cpu(void)
@@ -41,6 +42,7 @@ void doorbell_exception(struct pt_regs *regs)
 
 	may_hard_irq_enable();
 
+	kvmppc_set_host_ipi(smp_processor_id(), 0);
 	__this_cpu_inc(irq_stat.doorbell_irqs);
 
 	smp_ipi_demux();